The invention concerns a method and device for the folding of ribbon cables.
Ribbon cables are known in the prior art and are increasingly used for different reasons in the automotive industry in the production of cable harnesses. Because of the strongly anisotropic mechanical properties of ribbon cables, bends and curves cannot be bent in the plane of ribbon cables (and naturally not in planes that include only a shallow angle relative to this plane). This is invariably necessary when a certain contour must be followed between the two ends of the ribbon cable (which ordinarily, but not necessarily, are provided with connectors).
It is then necessary to fold the ribbon cable so that a cable that essentially consists of a sequence of linear segments, in which adjacent segments are joined to each other by folding is obtained. It is inherent to the ribbon cable and this arrangement that the side of the ribbon cable that was the top (viewed geometrically) xe2x80x9cbeforexe2x80x9d folding is the bottom xe2x80x9cafterxe2x80x9d folding. If this is not admissible for whatever reason, a connection (for example, welding) between two (generally positioned one on the other) cable sections must be created instead of folding.
Such folds have thus far been made by means of devices that have corresponding stops or the like at the site at which a ribbon cable is to be folded. This means that in repeatedly folded ribbon cables, and this is the case in most cables, since the different contours of the auto body of the vehicle in which the cable harness is used must be traced, a number of folding stations must be arranged with high accuracy on the folding table. However, this also means that, even with only slight changes in the dimensions or outline of the cable harness, the entire table must be rearranged, which is naturally demanding and expensive.
The objective of the invention is therefore to devise a method and device of the type just mentioned that does not exhibit the mentioned shortcomings and can be rearranged and used cost-effectively for different cable harness sections of ribbon cables.
These objectives are achieved according to the invention in that the ribbon cable, with its first end, preferably already provided with the connector prescribed for this end, is brought into a predetermined initial position on the folding table and held in this position, for example, by means of a mating connector, a hold-down, or the like, that the other end of the ribbon cable, also preferably already provided with its connector prescribed for this end, is held and guided by a handling device, that an automatic handling device establishes the position and angular location of this end of the ribbon cable and, in the course of movement of this end, establishes the position change and stores it, and that a fold-forming device, preferably in the form of a roller, is arranged to be adjustable in height above the table and adjustable in position relative to the table, so that the position of the fold is defined by the geometric position of the two ends relative to each other and, with reference to the table and the fold, can be created with high accuracy by activation of the fold-forming device.
The table need not be flat, but can have a shape that enables it to form a ribbon cable so that it is reliably adapted to the curvature of a sunroof, a trunk, a door opening, etc.
The procedure according to the invention, in creating a corresponding section of the cable harness from a ribbon cable, is as follows: as already explained, the cable is first fastened to a predetermined point of the table with one end and held by a handling device with its other end, which is called the xe2x80x9cmanipulatedxe2x80x9d end. Due to knowledge of the instantaneous position of the manipulated end held by the handling device and knowledge of the final shape that the folded cable is to have, the computer belonging to the automatic handling device now calculates the position and angle of the first fold. It then rotates the manipulated end of the ribbon cable so that the transition from the top to the bottom of the cable is stipulated in the region of the fold; it brings the manipulated end of the ribbon cable into a position and angular position, in which this end must lie after the first fold is made.
By executing or creating this fold, the folding device now enters into action, preferably a roller This is placed close to the manipulated end on the ribbon cable and lolls away from the manipulated end to the site of the fold being formed. All bends and loops caused by the rigidity of the cable are smoothed out by this movement and the planned fold is produced by fixation of the ribbon cable in the correct end position at the predetermined site and with the predetermined angle.
The folding device is then raised from the table or remains in the fold region, preferably on the side of the fold facing away from the manipulated end of the ribbon cable, the automatic handling device brings the manipulated end of the ribbon cable into the location in position that it is supposed to have after formation of the second fold, and the folding device (or a second folding device, if the first is used for fixation of the first fold) again forms a fold, beginning in the region of the manipulated end.
It is naturally possible to provide two or more folding devices, in order to fix the regions lying between the ends during subsequent folding and to keep them in a predetermined position, especially in the long ribbon cables that must be folded frequently.
However, it is essential that the at least one folding device not be mounted in an unmovable manner, as in the prior art, at the location on the table prescribed for the fold, but that it be freely movable, just like the handling device for the manipulated end, by means of a computer and a corresponding electrical, pneumatic, or hydraulic drive device in the region of the table and thus to carry out, based on calculations of the computer, the corresponding movements over the table, in order to fold the cable situated between the table and the folding device. For adjustment to tolerances of any kind, the mentioned roller is preferred because it is then ensured that, in the first place, only the forces that are necessary for formation of the fold are transferred to the ribbon cable. It is naturally also possible to provide a type of flap or the like, through which the ribbon cable moves more or less simultaneously over a larger range of its length to the site of the desired fold and is folded there.
As is readily apparent from the explanation, it is an easy matter to create the different sections of a cable harness consisting of ribbon cables with the same table without rearrangement, since it is only necessary for this purpose that a different program be activated in the data processing unit for the handling device and the folding device. With respect to mechanical grasping of the cable end, it is an easy matter to create either a universal mount for the forms of the cable ends under consideration or coupling pieces that cooperate, on one end, with fixation on the folding table and fixation in the handling device and, on the other end, cooperate with corresponding cable ends, preferably the connectors already provided for final assembly. In this manner, with such intermediate pieces, it can also be ensured that the position of the cable end is always correctly recorded without having to perform complicated adjustment and calibration steps, since adjustment of small geometric differences or deviations can occur by the intermediate pieces used.
It is also essential that the individual errors of subsequent folds in the method according to the invention cannot be added in one direction since, during each fold, the manipulated end of the ribbon cable is held at the xe2x80x9ccorrectxe2x80x9d site with the stipulated accuracy, so that errors of the individual steps always balance each other out as best as possible.
Another advantage is that it becomes possible, with the method according to the invention, to connect the fold very tightly to an already existing fold, since no folding device fastened to the table hampers the folding process.